Relativistic Positioning Systems: The Emission Coordinates

This paper introduces some general properties of the gravitational metric and the natural basis of vectors and covectors in 4-dimensional emission coordinates. Emission coordinates are a class of space-time coordinates defined and generated by 4 emitters (satellites) broadcasting their proper time by means of electromagnetic signals. They are a constitutive ingredient of the simplest conceivable relativistic positioning systems. Their study is aimed to develop a theory of these positioning systems, based on the framework and concepts of general relativity, as opposed to introducing `relativistic effects' in a classical framework. In particular, we characterize the causal character of the coordinate vectors, covectors and 2-planes, which are of an unusual type. We obtain the inequality conditions for the contravariant metric to be Lorentzian, and the non-trivial and unexpected identities satisfied by the angles formed by each pair of natural vectors. We also prove that the metric can be naturally split in such a way that there appear 2 parameters (scalar functions) dependent exclusively on the trajectory of the emitters, hence independent of the time broadcast, and 4 parameters, one for each emitter, scaling linearly with the time broadcast by the corresponding satellite, hence independent of the others.Comment: 13 pages, 3 figures. Only format changed for a new submission. Submitted to Class. Quantum Gra

Compliance with the Municipal Agro-Environmental Legislation in Francisco de Orellana, Ecuador

The Decentralized Autonomous Municipal Government of the Francisco de Orellana canton is made up of the following rural parishes: Alejandro Labaka, Armenia, Dayuma, El Dorado, El Edén, García Moreno, Guayusa, Inés Arango, La Belleza, Nuevo Paraiso, Taracoa and the Urban Parish of El Coca. The Constitution of the Republic of Ecuador (2008) establishes the rights of nature and protects the biodiversity of the Amazon ecosystem. This is complemented by the provisions of the Organic Code of Territorial Organization, Autonomy and Decentralization (2010), the Organic Code of the Environment (2017) and also the Organic Law for the Integrated Planning of the Special Amazon Territorial District (2018). This article reviewed compliance with municipal agro-environmental legislation in the Decentralized Municipal Autonomous Government of the Francisco de Orellana canton. This analysis was based on the publication of the Organic Law for the Integrated Planning of the Special Territorial District of the Amazon in the Official Registry Supplement 245, dated May 21, 2018. A qualitative methodology was used. Data were collected through analysis of public policies, regulations, legislation and ordinances, and interviews with the main actors of the Decentralized Municipal Autonomous Government. The results suggested that the Municipal Government seeks to protect the biodiversity of the Amazon ecosystem by adopting sustainable development and conservation policies, but it is clear that ordinances are needed for agro-environmental education, garbage classification, recycling, organic gardens, and greater integration into municipal agro-environmental projects. Keywords: agriculture, Amazon, environment, biodiversity, municipal, Ecuador. Resumen El Gobierno Autónomo Descentralizado Municipal del cantón Francisco de Orellana está integrado por las Parroquias Rurales: Alejandro Labaka, Armenia, Dayuma, El Dorado, El Edén, García Moreno, Guayusa, Inés Arango, La Belleza, Nuevo Paraiso, Taracoa y la Parroquia Urbana de El Coca. La Constitución de la República del Ecuador (2008), establece los derechos de la naturaleza y protege la biodiversidad del ecosistema amazónico, esto se complementa con lo establecido en el Código Orgánico de Organización Territorial Autonomía y Descentralización (2010), el Código Orgánico del Ambiente (2017) y ademas la Ley Orgánica para la Planificación Integral de la Circunscripción Territorial Especial Amazónica (2018). Este artículo revisa el cumplimiento de la legislación agroambiental municipal en el Gobierno Autónomo Descentralizado Municipal del cantón Francisco de Orellana, este análisis se realiza a partir de la publicación de la Ley Orgánica para la Planificación Integral de la Circunscripción Territorial Especial Amazónica en el Registro Oficial Suplemento 245, de fecha 21 de mayo del 2018. La metodología utilizada se basó en un análisis cualitativo usando técnicas y herramientas como la obtención de datos, análisis de las políticas públicas, normativa, legislación, ordenanzas y entrevista con los principales actores del Gobierno Autónomo Descentralizado Municipal del cantón Francisco de Orellana. Los principales resultados sugieren que el Gobierno Municipal busque precautelar la biodiversidad del ecosistema amazónico, adoptando políticas de desarrollo sostenible y de conservación, pero es evidente que son necesarias ordenanzas encaminadas a la educación agroambiental, clasificación de la basura, reciclaje, huertos orgánicos, y una mayor integración en proyectos agroambientales municipales. Palabras clave: agricultura, Amazonía, ambiente, biodiversidad, municipal, Ecuador

Jet shapes in ep collisions at HERA

New measurements of the jet shape in ep collisions at HERA using the k_T-cluster jet algorithm are presented.Comment: 7 pages, 3 figures; plenary talk given at the 3rd UK Phenomenology Workshop on HERA Physics, Durham, UK, September 199

Ecotypic Adaptation of Medicago Polymorpha along a Gradient in Central Chile: Growth and Seed Production

Relative growth rate, total dry weight and seed yield on 19 accessions of burr medic (Medicago polymorpha L.) from different bioclimatic conditions, were assessed at Cauquenes (35°58’;72°17’W) in the subhumid mediterranean region. The accessions were sown in microplots over raised beds during two years (1991 and 1992), and swards cut periodically at 2, 6 and 10 cm height. There were significant differences between accessions in both total dry weight and seed yield (P \u3c 0.001, Table 1), but the interaction between accessions and height of cutting was not significant (P \u3e 0.05). Total dry weight was positive correlated with days to flowering (r2 = 0.81; P \u3e 0.01)

Topological Measure Locating the Effective Crossover between Segregation and Integration in a Modular Network

We introduce an easily computable topological measure which locates the effective crossover between segregation and integration in a modular network. Segregation corresponds to the degree of network modularity, while integration is expressed in terms of the algebraic connectivity of an associated hyper-graph. The rigorous treatment of the simplified case of cliques of equal size that are gradually rewired until they become completely merged, allows us to show that this topological crossover can be made to coincide with a dynamical crossover from cluster to global synchronization of a system of coupled phase oscillators. The dynamical crossover is signaled by a peak in the product of the measures of intra-cluster and global synchronization, which we propose as a dynamical measure of complexity. This quantity is much easier to compute than the entropy (of the average frequencies of the oscillators), and displays a behavior which closely mimics that of the dynamical complexity index based on the latter. The proposed toplogical measure simultaneously provides information on the dynamical behavior, sheds light on the interplay between modularity vs total integration and shows how this affects the capability of the network to perform both local and distributed dynamical tasks

Caveolin-1 Modulates Mechanotransduction Responses to Substrate Stiffness through Actin-Dependent Control of YAP

The transcriptional regulator YAP orchestrates many cellular functions, including tissue homeostasis, organ growth control, and tumorigenesis. Mechanical stimuli are a key input to YAP activity, but the mechanisms controlling this regulation remain largely uncharacterized. We show that CAV1 positively modulates the YAP mechanoresponse to substrate stiffness through actin-cytoskeleton-dependent and Hippo-kinase-independent mechanisms. RHO activity is necessary, but not sufficient, for CAV1-dependent mechanoregulation of YAP activity. Systematic quantitative interactomic studies and image-based small interfering RNA (siRNA) screens provide evidence that this actin-dependent regulation is determined by YAP interaction with the 14-3-3 protein YWHAH. Constitutive YAP activation rescued phenotypes associated with CAV1 loss, including defective extracellular matrix (ECM) remodeling. CAV1-mediated control of YAP activity was validated in vivo in a model of pancreatitis-driven acinar-to-ductal metaplasia. We propose that this CAV1-YAP mechanotransduction system controls a significant share of cell programs linked to these two pivotal regulators, with potentially broad physiological and pathological implications. Moreno-Vicente et al. report that CAV1, a key component of PM mechanosensing caveolae, mediates adaptation to ECM rigidity by modulating YAP activity through the control of actin dynamics and phosphorylation-dependent interaction of YAP with the 14-3-3-domain protein YWHAH. Cav1-dependent YAP regulation drives two pathophysiological processes: ECM remodeling and pancreatic ADM. © 2018 The Author

La "máquina" o "generador" de terremotos en un laboratorio universitario

La máquina o generador de terremotos es un dispositivo experimental que trata de modelizar el comportamiento de una falla. En la actividad propuesta, se le muestra al alumnado la complejidad de ciertos sistemas, así como la dificultad de predecir su comportamiento. Aunque inicialmente se postuló como un experimento abierto dirigido a estudiantes de enseñanza secundaria y bachillerato, la calidad de los datos que pueden obtenerse permite que pueda plantearse como un experimento en unlaboratorio universitario de ciencias de la Tierra. Los datos obtenidos en una experiencia de este tipo pueden ser equiparables, en cierto sentido, a los datos obtenidos por redes sísmicas regionales, en especial, los datos referentes a la sismicidad generada por una falla o sistema de fallas, en términos de magnitud, tiempo y caída de esfuerzos. Eso sí, con la clara ventaja de que en pocos minutos puede reproducirse lo que serían cientos o miles de años de acción de las fuerzas tectónicas. En función del nivel del curso en el que se proponga dicha experiencia, planteándose en este caso como una experiencia cerrada centrada en la obtención de determinados resultados, se pueden utilizar diferentes análisis de datos, fundamentalmente de tipo estadístico. Estos análisis permitirán conocer el nivel de predictibilidad de un modelo de estas características. Este trabajo plantea diferentes métodos y analiza los resultados que pueden obtenerse con este modelo mecánic

Causal symmetries

Based on the recent work \cite{PII} we put forward a new type of transformation for Lorentzian manifolds characterized by mapping every causal future-directed vector onto a causal future-directed vector. The set of all such transformations, which we call causal symmetries, has the structure of a submonoid which contains as its maximal subgroup the set of conformal transformations. We find the necessary and sufficient conditions for a vector field \xiv to be the infinitesimal generator of a one-parameter submonoid of pure causal symmetries. We speculate about possible applications to gravitation theory by means of some relevant examples.Comment: LaTeX2e file with CQG templates. 8 pages and no figures. Submitted to Classical and Quantum gravit